People who smoke only about 1 cigarette per day carry the risk of developing coronary heart disease (CHD) and stroke about half that of those who smoke 20 cigarettes per day, a recent study found. The meta-analysis included 141 cohort studies with at least 50 events reported hazard ratios (HRs) or relative risks (RRs) compared with never smokers or age-specific incidence in relation to risk of CHD or stroke. Researchers found:

Men who smoke ∼1 cigarette per day have a 48% higher risk of heart disease than never smokers and a 25% higher risk of stroke.

Women who smoke ∼1 cigarette per day have a 57% higher risk for heart disease and a 31% higher risk for stroke compared with never smokers.

People who smoke ∼1 cigarette per day have about 40-50% of the excess risk associated with smoking 20 cigarettes per day.

The authors cautioned that there is no safe level of smoking for cardiovascular disease.

This study answers the commonly asked question, “How important is it to stop smoking versus cutting down on the number of cigarettes daily?” Interestingly, the proportion of smokers who consume < 10 cigarettes per day has increased from 16% to 27% in the US between 2005 and 2014, so this has become an increasingly important question.1 While many, if not most people, believe that cutting down on the number of cigarettes smoked might lead to a proportional decrease in risk of heart disease, with smoking 1 cigarette giving only 5% of the risk of smoking a pack of cigarettes a day, this does not appear to be the case. Smoking cigarettes, in any amount, substantially increases the risk of cardiovascular disease. — Neil Skolnik, MD